# Refilling butane



## Darkavenger (Apr 17, 2011)

Do you let the air out before you refill Everytime?


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## anthony d (May 10, 2014)

Yes, absolutely.


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## scrouds (Mar 29, 2014)

I do if I want anywhere close to a full tank.


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## Emperor Zurg (May 6, 2013)

Never.

Put the lighter in the fridge for an hour before filling it.


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## MDSPHOTO (Sep 10, 2013)

Yep I always drain mine.


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## Darkavenger (Apr 17, 2011)

I always have just wondering if that was the general consensus. I did manage to spray butane all over my face today. Damn lighter not having a spot to see the amount of butane in it


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## AuTechCoM (Jan 13, 2014)

I always do. with my Xikar if i don't drain it first i can only get a drop or two of butane in


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## hachigo (Feb 14, 2012)

I'm with most others, always do.


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## madbricky (Mar 29, 2013)

Yes sir! Can down, lighter bottoms up. This prevents the issue with mislights too. You know who is a lighter expert? KAYLA from @CheapHumidors / Buylighters.com As a matter of fact she is a bonfire of cigar knowledge and I follow her blog on the Cheaphumidors.com website. Good people to know! Her fiancé is also knowledgeable and I think fancies a NFL guru....lol


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## CheapHumidors (Aug 30, 2007)

madbricky said:


> Yes sir! Can down, lighter bottoms up. This prevents the issue with mislights too. You know who is a lighter expert? KAYLA from @CheapHumidors / Buylighters.com As a matter of fact she is a bonfire of cigar knowledge and I follow her blog on the Cheaphumidors.com website. Good people to know! Her fiancé is also knowledgeable and I think fancies a NFL guru....lol


Ha! Thanks Craig! I agree, definitely let all the air out first. Makes for a better light


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## Ricardo- (Feb 26, 2014)

Ok. Dumb question. How do you let the air out?


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## CheapHumidors (Aug 30, 2007)

Ricardo- said:


> Ok. Dumb question. How do you let the air out?


No question is a dumb question. Press the butane valve with a pen or small screwdriver until it stops hissing, then press the ignition switch a couple of times until it stops hissing.


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## Darkavenger (Apr 17, 2011)

Good suggestion I've never clicked the lighter to make sure the air was out. I've just pressed the valve.


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## Ricardo- (Feb 26, 2014)

CheapHumidors said:


> No question is a dumb question. Press the butane valve with a pen or small screwdriver until it stops hissing, then press the ignition switch a couple of times until it stops hissing.


Thanks Kayla. Hmmm.... Never done this and I never thought I was not filling it right. It lasts for several days, but I guess I could do better. The problem I see is that you have to wait until it's empty of close to empty, right? I'll have to try this sometime.


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## CheapHumidors (Aug 30, 2007)

Ricardo- said:


> Thanks Kayla. Hmmm.... Never done this and I never thought I was not filling it right. It lasts for several days, but I guess I could do better. The problem I see is that you have to wait until it's empty of close to empty, right? I'll have to try this sometime.


Correct, otherwise you are wasting a lot of fuel.


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## FlipMo (Oct 1, 2013)

Yes! I was told to always purge the lighter before refills. Even if the lighter is out of butane, I still purge and can hear a bit of a "hiss" when purging. I just think it makes the lighter last longer and have fewer problems in the long run. It can't hurt, right?


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## KaChong (Jan 1, 2012)

There is no need to "purge" a lighter except possibly on it's very first fill when it might contain some air. There is no air in a butane can. If it's butane intended for lighter fuel, it will have practically no air.

The problem faced when filling a lighter is that liquid butane will transfer until the pressure in the lighter has equalized with the pressure in the can. If the can pressure does not exceed the pressure in the lighter, no further transfer can occur. Before you say "ideal gas law" think about the regime that the Idealized Gas Laws apply: conditions far from 2 phase conditions. The liquid phase of butane in our lighters is clearly a condition that does not obey idealized gas laws because the gas is at saturation conditions. PV != nRT

Bla bla bloo blah... What does this mean? The pressure in your lighter will be governed by only one variable (a new idealization of saturated gas conditions) where the pressure will be constant as long as there is liquid present at a fixed temperature. If you want to move more liquid, you need to get your lighter to be colder than your can. That's it.

You can "purge" your lighter which will evaporate a bunch of liquid butane which will chill your lighter which facilitates filling, or you can put it in the fridge for maybe 10min and it'll take a full fill easily.


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## Drez_ (Jan 30, 2014)

I never do on mine, but I also never wait until it is near empty to refill it. I keep it topped off every couple of days, and never have any problems withlighting or sputtering. I also never have a problem getting the light full. (Viewable tank so I know its full) or wasting butane. Have been using the same can for months now on a number of lighters.


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## Emperor Zurg (May 6, 2013)

KaChong said:


> There is no need to "purge" a lighter except possibly on it's very first fill when it might contain some air. There is no air in a butane can. If it's butane intended for lighter fuel, it will have practically no air.
> 
> The problem faced when filling a lighter is that liquid butane will transfer until the pressure in the lighter has equalized with the pressure in the can. If the can pressure does not exceed the pressure in the lighter, no further transfer can occur. Before you say "ideal gas law" think about the regime that the Idealized Gas Laws apply: conditions far from 2 phase conditions. The liquid phase of butane in our lighters is clearly a condition that does not obey idealized gas laws because the gas is at saturation conditions. PV != nRT
> 
> ...


HOLY SHIZNIT, BATMAN! Here's someone who actually understands the concept of 'pressure at temperature' in regards to a liquified gas! Not to mention the (apparently mind boggling) concept that just because something is a clear gas, it's NOT NECESSARILY AIR.

All this talk of 'purging the air' out of your lighter is pure nonsense. There are 2 things in the fuel tank of a lighter - and for that matter, a butane can: butane gas and butane liquid. Just chill the lighter to make it considerably colder than the butane can and the lighter will fill right up to the top. Trouble is, usually you're taking your lighter directly out of your toasty warm pocket and attempting to fill it with a room temp butane can. Not going to work; thus all this talk about 'purging the air' in order to make room for butane when all you're really doing is chilling the fuel tank slightly by releasing the last remnants of butane.


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## Keeper01 (Mar 1, 2014)

A lot of very good information here. I didn't know there was a science behind getting a better fill on a lighter. I'm going to start chilling mine before refilling.


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## KaChong (Jan 1, 2012)

One other trick comes to mind. I use it when I'm in a hurry and need to fill butane fast. Perhaps just before dashing out the door to herf.

I turn the lighter upside down and ignite it. Blow out the flame leaving gas hissing out the torch end while filling from the topside fill valve. It can be a bit awkward to hold the lighter doing this, but it works. Filling while venting prevents the pressure inside the lighter reservoir from equalizing with your can pressure. While gas is leaking out the torch end, liquid is being injected into the fill valve. You have to be completely sure that the flame is out for safety reasons.


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## AuTechCoM (Jan 13, 2014)

All of the info you guys just gave us makes perfect sense... But my only questions is if simply cooling you lighter is good enough why would the lighter manufacturers suggest bleeding the lighter? Is it as simple as them getting us to waste butane so we buy more? or do they have a reason?


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## Emperor Zurg (May 6, 2013)

AuTechCoM said:


> All of the info you guys just gave us makes perfect sense... But my only questions is if simply cooling you lighter is good enough why would the lighter manufacturers suggest bleeding the lighter? Is it as simple as them getting us to waste butane so we buy more? or do they have a reason?


Probably because when the lighter is brand new and the tank is truly empty of butane, it does indeed contain air that could probably stand to be bled out. They probably figure you're not smart enough to differentiate between first fill procedure and subsequent fills so they just tell you to bleed it every time.

One other possible reason is that it's possible to fill the lighter 100% if you chill it enough first which would not leave any room for expansion of the liquid as it warms up. In this case, as the lighter warms up in your pocket, the expanding, liquid butane would simply dead-head and hydraulically fracture the lighter tank. I always burn min for about 30 seconds after a fill to make sure there's a little room in there for expansion.


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## Ky70 (Aug 21, 2012)

If I'm heading out and the lighter I want to take has some a fuel in it, I top it off. If I have a lighter that runs out or is close to running it out, I purge it before refilling. So I do both and am not really concerned about it. 

I find the type of butane used is more important than the purge/don't purge question. I have a quite a few butane lighters (some around 10 years old) and they all are in excellent working condition. I use vector fuel.


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## KaChong (Jan 1, 2012)

I've tried getting a lighter to dead head and pop, but I've never seen it happen yet. Still I too bleed mine out for about 5-10 seconds to prevent that issue from happening.


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## Herf N Turf (Dec 31, 2008)

One thing you frigid proponents fail to accommodate is the fact that you can never, ever get all the air out of a lighter. Even when you purge it, there will still be residual air inside. You can chill and throw all the butane in the world on top of it, but there will still be air in there. When the mixture of said air to butane becomes too great, the lighter will fail to ignite. Purging discharges the _excess_ air and allows a greater volume of butane to take its place. KaChong's method of open valve filling is the best way to ensure maximum displacement of air, since it allows the butane to effectively push the air out the valve.

Before anyone gets his panties in a knot, chilling a lighter does work better than not.


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## Emperor Zurg (May 6, 2013)

Herf N Turf said:


> One thing you frigid proponents fail to accommodate is the fact that you can never, ever get all the air out of a lighter. Even when you purge it, there will still be residual air inside. You can chill and throw all the butane in the world on top of it, but there will still be air in there. When the mixture of said air to butane becomes too great, the lighter will fail to ignite. Purging discharges the _excess_ air and allows a greater volume of butane to take its place. KaChong's method of open valve filling is the best way to ensure maximum displacement of air, since it allows the butane to effectively push the air out the valve.
> 
> Before anyone gets his panties in a knot, chilling a lighter does work better than not.


Where did this air come from then?


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## madbricky (Mar 29, 2013)

You and the other guy do it your way, but your just hissing a lot of gas if you don't understand that it's a problem with air getting into most lighters over time. Maybe your Bat-lighter is perfectly sealed.


Emperor Zurg said:


> HOLY SHIZNIT, BATMAN! Here's someone who actually understands the concept of 'pressure at temperature' in regards to a liquified gas! Not to mention the (apparently mind boggling) concept that just because something is a clear gas, it's NOT NECESSARILY AIR.
> 
> All this talk of 'purging the air' out of your lighter is pure nonsense. There are 2 things in the fuel tank of a lighter - and for that matter, a butane can: butane gas and butane liquid. Just chill the lighter to make it considerably colder than the butane can and the lighter will fill right up to the top. Trouble is, usually you're taking your lighter directly out of your toasty warm pocket and attempting to fill it with a room temp butane can. Not going to work; thus all this talk about 'purging the air' in order to make room for butane when all you're really doing is chilling the fuel tank slightly by releasing the last remnants of butane.


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## KaChong (Jan 1, 2012)

I don't usually try to qualify my technical posts with a bunch of letters behind my name, but I find that sometimes the acceptance of information needs to be delivered in a manner that unfortunately isn't in the form of a rational statement.

I am a mechanical engineer by training which involves the study of two phase systems, like refrigeration and steam cycle loops which pertains to the behavior of liquid butane crammed into a pressure vessel. Furthermore I have some significant experience designing small refillable liquid propane devices which employ very similar valves to the kind we see in butane lighters. I have designed valves for products marketed by my company, for which I am the design engineer:

Airsoft Innovations

Two products we carry that employ two phase liquid propane propulsion are our airsoft grenades and our small gas refil reservoirs. To assure that our customers can deliver an adequate fill to our products, we employ two port fill valves. Our valves have two ports that are opened when the fill tip from a filling can is applied. One passage connects the fill tip to the reservoir for the transfer of liquid propellant. A second, small area, bypass port also opens up which allows the escape of gas from the fill reservoir while filling. This secondary port provides an INTENTIONAL leak which sounds kind of shitty, but it assures that liquid can be transferred to our product even if our reservoirs start out at a higher temperature than the filling can. We also employ an overflow feature which prevents 100% fill for two reasons. For our grenade product, the overflow assures that a significant gas space is provided which provides a harder initial thrust to propel projectiles. If the grenade were to receive a 100% fill, liquid would have to evaporate rapidly to provide boost pressure. This would greatly reduce the power of the output of our device so our liquid fill volume is calculated to provide maximum pre expanded gas yet also store enough liquid to have sufficient persistence of thrust to discharge all projectiles.

Our portable refill can product also has an overflow pipe, but not for the same reason as our grenade. Our overflow pipe is intended to PREVENT 100% filling of our product to prevent "deadheading" our reservoir. If a reservoir is filled with absolutely no gas space, the pressure within the container will be a function of the thermal coefficient of expansion of a fairly incompressible liquid. This can be a dangerous situation as the pressures that can be reached in 100% full containers can be very high. For this reason DOT compliant disposable pressure vessels like Coleman propane cans are only filled to 80% of their volumetric capacity. Aerosol type cans also follow a similar 80% max fill specification and so does paintball industry in rating the capacity of CO2 tanks.

The pressure behavior of two phase systems like a gas-liquid butane system is an odd one. It isn't like having a slug of air in a syringe. Compress the air to half it's volume and the pressure will double. Once you have "equilibrium" conditions where there is the existence of gas and liquid you actually have met conditions where gas is spontaneously condensing to liquid as fast as liquid is evaporating to gas. You can shift this equilibrium point by changing temperature. Heating the reservoir will evaporate some liquid to gas until the pressure of the gas increases and establishes a new equilibrium again. Basically the long and short simplification of it is that as long as there is liquid present you will have the same pressure so long as the temperature is fixed. It's a very handy effect to exploit. It means that your butane lighter will output the same pressure and burn performance whether it is 80% full or 10% full. As with many things, nature is a bitch. Once you deplete below 10% you start to see some transition behavior and your constant pressure curve starts to drop down.

Since two port valves are not generally employed by the designers of cigar lighters, one has to apply some ingenuity to significantly fill their lighters which are likely to be equipped with single port valves. You could warm your filling can with warm water, but you do kind of risk overpressurizing it. DOT cans have to be able to handle 75C without bulging or exploding, but it still seems to be a dumb idea. Besides, a warm can would be injecting warm liquid butane into your lighter which means that the pressure in the target reservoir will equalize quickly with the can. Starting with a cold lighter is preferable. As warmer liquid is injected during the fill, it is cooled by the lighter which means it will exert a lower pressure than the liquid in the can. Lower pressure in the lighter facilitates ongoing liquid transfer.

_*FUNNY PROBLEM WITH PURGING A NEARLY EMPTY LIGHTER HERE:*_
You can exhaust the remaining gas to cool your lighter. Exhausting the gas will boil off remaining liquid and absorb heat from the lighter body in the process. This chills the interior of your lighter, but perversely if you have a nearly empty lighter you will have very little liquid butane to absorb heat and blow out an open valve. The worst case scenario would be to have a pocket warm lighter with almost no residual liquid butane inside. You would have almost no liquid to evaporate and chill the lighter and you'd start your fill with a warm lighter.

Chilling your lighter in the fridge works well because it cools the entire body of the lighter. This is good because you get a lot of material cold to heat sink the liquid to be filled with. If you really want to try to dead head your lighter put your lighter in the freezer for half an hour before filling. You do risk damaging certain rubber seals which don't shift as well when they're that cold. I tried to see if one of my lighters would exploded when it was dead headed, but instead the fill valve seal got nicked during it's actuation and never sealed shut again. Still you shouldn't intentionally dead head a lighter. I find I get crazy burn performance with overfilled lighters anyways because they have a higher fill pressure.

Anyways, thanks for reading if you made it down this far. I hope this helps you get better performance out of your butane and butane powered accessories.


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## Ricardo- (Feb 26, 2014)

Buy a BIC. Problem solved.

Seriously, How much of a difference does it really make? You'll need to refill eventually.

I never thought about this and was able to sleep very well every night.

Carry on.


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## anthony d (May 10, 2014)

Ok, so I can either put my lighter in the fridge for 10 minutes, or purge it in 30 seconds.

Both accomplish the same thing it seems.

I'll take the 30 second purge.


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## Engineer99 (Aug 4, 2011)

I have a hard time understanding how pressure can build up enough to eject air, when the pressurized tank is slowly being relieved of the pressure caused from the expansion/vaporization of liquid fuel into any air space within. One would think it would suck air in since contents are being removed without being replaced, creating a vacuum within the tank. It would seem to me that "purging" is just releasing whatever butane vapor pressure remaining in the tank out the back end instead of out the top where they normally exit to make the flame.

I've never purged my lighters and have never had any problems topping them off or getting a good light.


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## anthony d (May 10, 2014)

For me, and again, I am relatively new to this, I don't refill my lighter until it doesn't light anymore. When that happens, a decent amount of pressure is still released when I hold down the bleed valve. It takes all of about 30 seconds to bleed it out, and it immediately takes a full charge of butane afterwards. I don't get sprayed in the face by butane or anything when I purge.


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## AndyRN (Oct 24, 2012)

I don't do anything to my lighters before I fill them and they work fine. I would love to know if purging or throwing the lighter in the fridge actually gets us anymore lights. I understand the science behind doing so; however, in practical application it is probably negligible. I think the biggest factor in number of lights per refill is ambient temperature when the lighter is actually being used.


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## madbricky (Mar 29, 2013)

Good on you for keeping it simple! Too many have gone before us giving simple fixes for such things as air mixed with butane in the tank or whatnot, no degree in mechanical engineering required.


anthony d said:


> For me, and again, I am relatively new to this, I don't refill my lighter until it doesn't light anymore. When that happens, a decent amount of pressure is still released when I hold down the bleed valve. It takes all of about 30 seconds to bleed it out, and it immediately takes a full charge of butane afterwards. I don't get sprayed in the face by butane or anything when I purge.


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## Herf N Turf (Dec 31, 2008)

Emperor Zurg said:


> Where did this air come from then?


I think it's fairly safe to assume that lighters are not built in a vacuum chamber 

Even if they were, the valve would still pull air through it in order to equalize the vacuum.


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## Rennsport1150 (May 14, 2014)

Vacuum :twitch:


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## SeanTheEvans (Dec 13, 2013)

@KaChong

Thanks for quite the informative post. I seriously enjoy when someone who absolutely knows what they are talking about on a technical level can explain how some things work. At the same time, apparently people do a lot of other things that seem to work as well, and we still have no measurement for this. If I find time this upcoming week I will attempt to rectify the situation with some hard data.


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## Rennsport1150 (May 14, 2014)

Ideally in trying situations like this it is really comforting to have friends such as Messrs Boyle & Dalton


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## 11GTCS (May 20, 2014)

KaChong said:


> There is no need to "purge" a lighter except possibly on it's very first fill when it might contain some air. There is no air in a butane can. If it's butane intended for lighter fuel, it will have practically no air.
> 
> The problem faced when filling a lighter is that liquid butane will transfer until the pressure in the lighter has equalized with the pressure in the can. If the can pressure does not exceed the pressure in the lighter, no further transfer can occur. Before you say "ideal gas law" think about the regime that the Idealized Gas Laws apply: conditions far from 2 phase conditions. The liquid phase of butane in our lighters is clearly a condition that does not obey idealized gas laws because the gas is at saturation conditions. PV != nRT
> 
> ...


Ironically, by purging a lighter (and bringing it to equib with the atmosphere) you're introducing air into the tank, which makes things worse in the long run, since air is less readily compressible and will keep your tank from filling correctly. I noted this when modding a jetlite, and had to purge the air out by filling while having the jet slightly open to force air out.


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## billjohnson (Mar 4, 2012)

KaChong said:


> There is no need to "purge" a lighter except possibly on it's very first fill when it might contain some air. There is no air in a butane can. If it's butane intended for lighter fuel, it will have practically no air.
> 
> The problem faced when filling a lighter is that liquid butane will transfer until the pressure in the lighter has equalized with the pressure in the can. If the can pressure does not exceed the pressure in the lighter, no further transfer can occur. Before you say "ideal gas law" think about the regime that the Idealized Gas Laws apply: conditions far from 2 phase conditions. The liquid phase of butane in our lighters is clearly a condition that does not obey idealized gas laws because the gas is at saturation conditions. PV != nRT
> 
> ...


Well done sir. Perfect analysis and conclusion. :bowdown:


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## LegoMaximus (May 8, 2014)

i always turn the flame down when refilling then turn it back to where you want it it seems to fill alot better.


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## Keeper01 (Mar 1, 2014)

Check out the thread that I posted about chilling your lighter. No need to purge when you do this.


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## Fuzzy (Jun 19, 2011)

I hold my breath while filling all my lighters. I also only have good thoughts of smoking nice dark Nicaraguan tobacco. My Zen and the art of the refill.

I only wish I had a lighter that I could refill from the large propane tank built into my home.


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## magoo6541 (Mar 9, 2014)

I do only because the directions say that you should. If I need to send my lighter in for service, I can honestly say that I followed the directions.


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